Venomous jellyfish have a significant economic and health impact on man and possess a number of physiological activities of biomedical interest. The sea nettle, a venomous jellyfish found in abundance in the Chesapeake Bay, can inflict pain in man and the venom produces a lethal cardiac effect in mice. This cardiotoxin is similar in action to that of the sea wasp and may serve as a model for the investigation of that venom. The neurotoxin and kinin-like principles present in sea nettle venom may contribute to the production of pain. Efforts will be made to isolate and chemically characterize the neurotoxic, pain producing, kinin-like and cardiotoxic factors of the venom. A better definition of the chemical nature of nematocyst toxins and the pathogenesis of the sting is necessary in order to understand and eliminate the nettle as a nuisance to man. A higher degree of purification of the pain and lethal factors of the venom will be attempted through use of affinity chromatography. The progress of purification will be followed by analytical thin layer isoelectric focusing and disk gel electrophoresis. A rapid assay system for measuring the toxicologic actions of the venom will involve use of purified antibody. The action of the neurotoxin will be defined by differentiating whether its action is directed against the postganglionic membrane or the acetylcholine transmitter. Acetylcholine and cholinesterase will be measured by microchemical techniques in the lobster neuron before and after venom injection. In order to determine whether the venom affects the postganglionic membrane rather than only acetylcholine, the effect of the venom on a neuron which employs a non-acetylcholine transmitter (GABA) will be studied on a nerve-muscle preparation. The kinin-like and cardiac effects of isolated toxins will be investigated and compared with those found in other coelenterate venoms.